Botulinum Toxin

shevyatiwari's version from 2015-08-21 10:12


Question Answer
C botulinum produces 3 serologically distinct neurotoxinsF, 7 (A-G)
All potentiate AcHF, inhibit ACH neurotransmitter release from NMJ -> flaccid muscle paralysis
Size of 260kDaF, 150
They are attached to larger proteins to aid excretionF, to aid absorption and protect against acidic environment in the gut and degradative effects of intestinal proteases
the LC binds to the presynaptic terminal and the HC enters and cleave proteins required for ACH releaseF, other way around
Neurotoxin F and G have little effect on humansF, C and D have little effect
Serotype A is the weakest in humansF, most potent
SNARE are heavy chain targetsF,light
A, C, E catalyse cleavage of SNARE protein SNAP25T
B, D, F, G catalyse cleavage of VAMPT
Syntaxin, MUNC-18 are not targets of BoNTF
Muscle weakness is seen in 1 dayF, 2-4 days
Maximal paralysis occurs in 2-4 daysF, 7-10 days
In 14 months, new SNARE proteins are generatdF, 1 month
After 6 months, functional connection is reestablishedF, 3 months
Muscle atrophy improves with each BoNT treatmentF, worsens
1 unit is the amount used to kill 50 miceF, to kill 50% of mice
Humans need approx 5 units to dieF, 250-300 units
Neutralising antibodies can form against the coreT
BoNTA are heat sensitive - need to be stored in the freezerT, or fridge
Should be reconstituted with salineF, best with saline preserved wtih benzyl alcohol (less pain- and same efficacy)
Cat BF, C
Absolute C/I include hypersensitivity and pregnancyF, hypersensitivity and infection at injection site
Known neruomuscular disease is a relative C/I to BotoxT
Antibody production precludes treatment from all serotypes of botulinF, serotpye speific
Most adverse effects are a result of the toxinF, injection technique complications
Toxin diffuses approx 5-10cmF, 1-3cm
Remain upright 24 hours laterF, 2-4 hours
Perform exaggerated muscle movementsT
Weakness of surrounding muscles can last 3-6 monthsT
a adrenergic agonist eye drops can help disguise eyelid and mild brow ptosisT
Weakness of the hands can last several weeksT, nerve studies can show abnormalities for longer
Improvements should be seen in 2/52T

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